Attempts have been made by philologists to
reach conclusions about the origin of the flowering of
civilization in southern Mesopotamia by the
analysis of Sumerian words. It has been thought
possible to isolate an earlier, non-Sumerian
substratum from the Sumerian vocabulary by
assigning certain words on the basis of their endings to either a
Neolithic or a Chalcolithic
language stratum. These attempts are based on the phonetic
character of Sumerian at the beginning of the
2nd millennium BC, which is at least 1,000 years later than the
invention of writing. Quite apart, therefore,
from the fact that the structure of Sumerian
words themselves is far from adequately investigated, the
enormous gap in time casts grave doubt on the criteria used to
distinguish between Sumerian and "pre-Sumerian"
vocabulary.

The earliest peoples of Mesopotamia who can
be identified from inscribed monuments and written tradition--[people
in the sense of speakers of a common language]--are, apart
from the Sumerians, Semitic
peoples (Akkadians or pre-Akkadians)
and Subarians (identical with, or near relatives
of, the Hurrians, who appear in northern Mesopotamia
around the end of the 3rd millennium BC). Their presence is
known, but no definite statements about their past or possible
routes of immigration are possible.

At the turn of the 4th to 3rd millennium BC, the long span of prehistory
is over, and the threshold of the historical era
is gained, captured by the existence of writing.
Names, speech, and actions are fixed in a system that is composed
of signs representing complete words or syllables. The signs may
consist of realistic pictures, abbreviated representations, and
perhaps symbols selected at random. Since clay is not well suited
to the drawing of curved lines, a tendency to use straight lines
rapidly gained ground. When the writer pressed the reed in harder
at the beginning of a stroke, it made a triangular
"head," and thus "wedges" were impressed into
the clay.

It is the Sumerians who are usually given the
credit forr the invention of this, the first system of writing in
the Middle East. As far as they can be assigned to any language,
the inscribed documents from before the dynasty of Akkad
(c. 2334-c. 2154 BC) are almost exclusively in Sumerian.
Moreover, the extension of the writing system to include the
creation of syllabograms by the use of the sound of a logogram
(sign representing a word), such as gi, "a
reed stem," used to render the verb gi,
"to return," can only be explained in terms of the Sumerian
language. It is most probable, however, that Mesopotamia
in the 4th millennium BC, just as in later times, was composed of
many races. This makes it likely that, apart
from the Sumerians, the interests and even
initiatives of other language groups may have played their part
in the formation of the writing system.

Many scholars believe that certain clay objects or tokens that
are found in prehistoric strata may have been
used for some kind of primitive accounting.
These tokens, some of which are incised and which have various
forms, may thus be three-dimensional predecessors of writing.

Sumerian is an agglutinative language: prefixes
and suffixes, which express various grammatical
functions and relationships, are attached to a noun
or verb root in a "chain."
Attempts to identify Sumerian more closely by
comparative methods have as yet been unsuccessful and will very
probably remain so, as languages of a comparable type are known
only from AD 500 (Georgian) or 1000 (Basque)--that
is, 3,000 years later. Over so long a time, the rate of change in
a language, particularly one that is not fixed in a written norm,
is so great that one can no longer determine whether apparent
similarity between words goes back to an original relationship or
is merely fortuitous. Consequently, it is impossible to obtain
any more accurate information as to the language group to which
Sumerian may once have belonged.

The most important development in the course of the 4th
millennium BC was the birth of the city. There
were precursors, such as the unwalled prepottery settlement at Jericho
of about 7000 BC, but the beginning of cities with a more
permanent character came only later. There is no generally
accepted definition of a city. In this context, it means a
settlement that serves as a centre for smaller settlements, one
that possesses one or more shrines of one or more major deities,
has extensive granaries, and, finally, displays an advanced stage
of specialization in the crafts.

The earliest cities of southern Mesopotamia,
as far as their names are known, are Eridu, Uruk,
Bad-tibira, Nippur, and Kish
(35 miles south-southeast of Baghdad). The
surveys of the American archaeologist Robert McCormick
Adams and the German archaeologist Hans Nissen
have shown how the relative size and number of the settlements
gradually shifted: the number of small or very small settlements
was reduced overall, whereas the number of larger places grew.
The clearest sign of urbanization can be seen at
Uruk, with the almost explosive increase in the
size of the buildings. Uruk Levels VI
to IV had rectangular buildings covering areas
as large as 275 by 175 feet. These buildings are described as temples,
since the ground plans are comparable to those of later buildings
whose sacred character is beyond doubt, but other functions, such
as assembly halls for noncultic purposes, cannot be excluded.

The major accomplishments of the period Uruk VI
to IV, apart from the first inscribed tablets
(Level IV B), are masterpieces of sculpture and of seal engraving
and also of the form of wall decoration known as cone
mosaics. Together with the everyday pottery of gray
or red burnished ware, there is a very coarse type known as the
beveled-rim bowl. These are vessels of standard size whose shape
served as the original for the sign sila, meaning "litre."
It is not too rash to deduce from the mass production of such
standard vessels that they served for the issue of rations. This
would have been the earliest instance of a system
that remained typical of the southern Mesopotamian city
for centuries: the maintenance of part of the population by
allocations of food from the state.

Historians usually date the beginning of history,
as opposed to prehistory and protohistory,
from the first appearance of usable written sources.
If this is taken to be the transition from the 4th to the 3rd
millennium BC, it must be remembered that this applies only to
part of Mesopotamia: the south,
the Diyala region, Susiana
(with a later script of its own invented locally), and the
district of the middle Euphrates, as well as Iran.